MyWebView.m

/* ***** BEGIN LICENSE BLOCK *****
# Copyright 2010 Alexandre Poirot
#
# Contributor(s):
#   Alexandre poirot <poirot.alex@gmail.com>
# 
# 
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either 
# version 2.1 of the License, or (at your option) any later version.
# 
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
# 
# You should have received a copy of the GNU Lesser General Public 
# License along with this library.  If not, see <http://www.gnu.org/licenses/>.
#
# ***** END LICENSE BLOCK *****/


#import "MyWebView.h"


@implementation MyWebView

- (id)initWithFrame:(CGRect)frame 
{
  if (self = [super initWithFrame:frame]) {
    
    // Set delegate in order to "shouldStartLoadWithRequest" to be called
    self.delegate = self;
    
    // Set non-opaque in order to make "body{background-color:transparent}" working!
    self.opaque = NO;
    
    // Instanciate JSON parser library
    json = [ SBJSON new ];
    
    // load our html file
    NSString *path = [[NSBundle mainBundle] pathForResource:@"webview-document" ofType:@"html"];
    [self loadRequest:[NSURLRequest requestWithURL:[NSURL fileURLWithPath:path]]];
    
  }
  return self;
}


// This selector is called when something is loaded in our webview
// By something I don't mean anything but just "some" :
//  - main html document
//  - sub iframes document
//
// But all images, xmlhttprequest, css, ... files/requests doesn't generate such events :/
- (BOOL)webView:(UIWebView *)webView2 
	      shouldStartLoadWithRequest:(NSURLRequest *)request 
	      navigationType:(UIWebViewNavigationType)navigationType {

	NSString *requestString = [[request URL] absoluteString];
  
  //NSLog(@"request : %@",requestString);
  
  if ([requestString hasPrefix:@"js-frame:"]) {
    
    NSArray *components = [requestString componentsSeparatedByString:@":"];
    
    NSString *function = (NSString*)[components objectAtIndex:1];
		int callbackId = [((NSString*)[components objectAtIndex:2]) intValue];
    NSString *argsAsString = [(NSString*)[components objectAtIndex:3] 
                                stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    NSArray *args = (NSArray*)[json objectWithString:argsAsString error:nil];
    
    [self handleCall:function callbackId:callbackId args:args];
    
    return NO;
  }
  
  return YES;
}

// Call this function when you have results to send back to javascript callbacks
// callbackId : int comes from handleCall function
// args: list of objects to send to the javascript callback
- (void)returnResult:(int)callbackId args:(id)arg, ...;
{
  va_list argsList;
  NSMutableArray *resultArray = [[NSMutableArray alloc] init];
  
  if(arg != nil){
    [resultArray addObject:arg];
    va_start(argsList, arg);
    while((arg = va_arg(argsList, id)) != nil)
      [resultArray addObject:arg];
    va_end(argsList);
  }

  NSString *resultArrayString = [json stringWithObject:resultArray allowScalar:YES error:nil];
  
  [self stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"NativeBridge.resultForCallback(%d,%@);",callbackId,resultArrayString]];
}

// Implements all you native function in this one, by matching 'functionName' and parsing 'args'
// Use 'callbackId' with 'returnResult' selector when you get some results to send back to javascript
- (void)handleCall:(NSString*)functionName callbackId:(int)callbackId args:(NSArray*)args
{
  if ([functionName isEqualToString:@"setBackgroundColor"]) {
    
    if ([args count]!=3) {
      NSLog(@"setBackgroundColor wait exactly 3 arguments!");
      return;
    }
    NSNumber *red = (NSNumber*)[args objectAtIndex:0];
    NSNumber *green = (NSNumber*)[args objectAtIndex:1];
    NSNumber *blue = (NSNumber*)[args objectAtIndex:2];
    NSLog(@"setBackgroundColor(%@,%@,%@)",red,green,blue);
    self.backgroundColor = [UIColor colorWithRed:[red floatValue] green:[green floatValue] blue:[blue floatValue] alpha:1.0];
    [self returnResult:callbackId args:nil];
    
  } else if ([functionName isEqualToString:@"prompt"]) {
    
    if ([args count]!=1) {
      NSLog(@"prompt wait exactly one argument!");
      return;
    }
        
    NSString *message = (NSString*)[args objectAtIndex:0];
    
    alertCallbackId = callbackId;
    UIAlertView *alert=[[[UIAlertView alloc] initWithTitle:nil message:message delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil] autorelease];
    [alert show];
    
  } else {
    NSLog(@"Unimplemented method '%@'",functionName);
  }
}

// Just one example with AlertView that show how to return asynchronous results
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
  if (!alertCallbackId) return;
  
  NSLog(@"prompt result : %d",buttonIndex);
  
  BOOL result = buttonIndex==1?YES:NO;
  [self returnResult:alertCallbackId args:[NSNumber numberWithBool:result],nil];
  
  alertCallbackId = nil;
}

@end